1. Filed of the Invention
The present invention relates to a lamp, and more particularly to a configuration of a vehicle lamp that employs LED lamps as a light source, along with its method of use.
2. Description of the Related Art
A vehicle lamp may be configured to employ LED lamps as a light source. In such a case, initially, the LED lamps can be aligned in a matrix of rows and columns, for example, on a surface of a printed circuit board. The LED lamps can be covered from above using a cover lens, such as a fish-eye lens, which has an appropriate lens cut. A lamp having a wide area of light emission is problematic, however, because it requires many LED lamps, which elevates costs and increases power consumption and heat radiation.
To solve such a problem, plural LED lamps can be aligned in a row so as to direct their optical axes perpendicular to a certain irradiation direction of the lamp. Fresnel lenses are located adjacent and corresponding to the LED lamps to change light from each LED lamp into a parallel light flux. In an optical path of the parallel light flux, plural stepped segments are provided in the irradiation direction of the lamp. Each segment has a reflective element and a step portion. This technology is effective to reduce the number of LED lamps because it allows replacement of the LED lamp type that includes rows and columns with an LED lamp type that includes one row (see JP-A 2003-059312, corresponding to U.S. Pat. No. 6,637,923 B2 which is hereby incorporated by reference).
In the above conventional configuration, the LED lamp also has a lens portion in addition to the Fresnel lens to achieve the parallel light flux. Thus, it can not completely achieve a parallel light flux which results in a considerable amount of light beams radiated in directions other than expected. These misdirected light beams can not be utilized as irradiation light from the lamp, resulting in a problem due to a lowered amount of light from the lamp.
In the above conventional configuration, separate components such as LED lamps, Fresnel lenses and segments are assembled. Accordingly, variations in accuracy during assembly or in component precision may cause variations in performance among products and can possibly complicate tests in quality control.